Acoustic manipulation of sound with soft material-based actuators

This thesis describes a unique parabolic acoustic manipulator with an inflatable structure, which has high gain and directivity. We created a morphable elastomeric reflecting surface with a diameter of 14 cm (6 in). Applying vacuum deforms the device into a concave structure, which provides directional amplification of incoming acoustic waves. In addition, the author characterized the impedance of the soft material employed in the acoustic reflector, Ecoflex 00-10, in an impedance tube. Ecoflex 00-10 has a measured reflection coefficient of approximately 0.9 at frequencies ranging from 500 Hz to 5000 Hz. This new characterization suggests this class of silicone-based elastomers is capable of advanced morphable devices to manipulate sound. Simulations also demonstrate that the soft reflecting surface is capable of transformation into a set of desired parabolic shapes between an initial planar geometry (neutral position) and a configuration with maximum curvature. With an applied vacuum, the membrane reaches its maximum deformation limited by the aluminum housing. At this stage of actuation, experimental results show the deformed membrane has similar gain and directionality (polar response) as rigid parabolic reflectors. This type of system might find future uses for adjustable parabolic microphones and long-range communication devices.M.S.Includes bibliographical referencesby Yanjun Wan